In November, 2015, Manuel Orobitg, student of the Master of
Oceanography and Management of the Marine Environment at the University of
Barcelona, presented his MSc Thesis “Morphology vs metabarcoding. A comparison
of techniques for biodiversity assessment in Maërl beds”, supervised by Xavier
Turon, Creu Palacin and Owen Wangensteen.
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| Image of the sampling of the Maërl community in Islas Cíes |
In this study, Manuel
analysed morphologically samples collected at the same time as the ones for the
genetic studies in the detritic bottoms of Islas Cies and Cabrera Archipelago.
He focused his analyses on three major groups: polychaetes, arthropods, and
molluscs. He identified at the lowest level possible, with the help of
taxonomists (a big thanks goes to Daniel Martin and Lídia Delgado), the species
present in the 10 and 1 mm filtrates, and obtained biomass values by weight.
The morphological analyses found 77, 45, and 44 morphospecies of polychaetes,
crustaceans, and molluscs, respectively, while the genetic technique yielded
182, 245, and 70 MOTUs, respectively, for the same size fractions. Thus,
metabarcoding allowed the determination of a higher diversity, but the
taxonomic precision attained was higher with morphology. On the other hand, all
structural parameters (biomass dominance curves, alpha- and beta-diversity patterns)
were markedly different between the metabarcoding and the morphology datasets,
indicating that both methods capture different aspects of the biodiversity
structure present. The morphological datasets tended to be quantitatively
dominated by a few species, while metabarcoding detected a more even distribution
of biomass of the dominant MOTUs.
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| Assortment of arthropods from the 1 mm fraction |
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